Fix unportable code in pgbench.

The buildfarm points out that UINT64_FORMAT might not work with sscanf;
it's calibrated for our printf implementation, which might not agree
with the platform-supplied sscanf.  Fall back to just accepting an
unsigned long, which is already more than the documentation promises.

Oversight in e6c3ba7fb; back-patch to v11, as that was.

src/bin/pgbench/pgbench.c

@@ -5019,16 +5019,19 @@ set_random_seed(const char *seed)
 	}
 	else
 	{
-		/* parse seed unsigned int value */
+		/* parse unsigned-int seed value */
+		unsigned long ulseed;
 		char		garbage;
 
-		if (sscanf(seed, UINT64_FORMAT "%c", &iseed, &garbage) != 1)
+		/* Don't try to use UINT64_FORMAT here; it might not work for sscanf */
+		if (sscanf(seed, "%lu%c", &ulseed, &garbage) != 1)
 		{
 			fprintf(stderr,
 					"unrecognized random seed option \"%s\": expecting an unsigned integer, \"time\" or \"rand\"\n",
 					seed);
 			return false;
 		}
+		iseed = (uint64) ulseed;
 	}
 
 	if (seed != NULL)